Field of the Invention
Embodiments in accordance with the present invention relate generally to photoimageable compositions containing certain thermal base generators (TBG) for forming microelectronic and/or optoelectronic devices and assemblies thereof, and more specifically to compositions encompassing polynorbornene (PNB) copolymers having norbornene-type repeating units and maleic anhydride type repeating units that exhibit improved crosslinking properties during the curing stage after patterning.
Description of the Art
Organic polymer materials are increasingly being used in the microelectronics and optoelectronics industries for a variety of applications. For example, the uses for such organic polymer materials include interlevel dielectrics, redistribution layers (RDL), stress buffer layers, chip stacking and/or bonding, leveling or planarization layers, alpha-particle barriers, passivation layers, among others, in the fabrication of a variety of microelectronic and optoelectronic devices. Where such organic polymer materials are photosensitive, thus self-imageable, and therefore, offer additional advantage of reducing the number of processing steps required for the use of such layers and structures made therefrom. Additionally, such organic polymer materials enable the direct adhesive bonding of devices and device components to form various structures. Such devices include microelectromechanical systems (MEMS), microoptoelectromechanical systems (MOEMS) and the semiconductor device encompassing a complementary metal oxide semiconductor (CMOS) image sensor dam structure, and the like.
While certain of the currently available organic photosensitive compositions are used in some of the aforementioned applications, there is still a need for organic photosensitive compositions which feature improved crosslinking properties after patterning especially in such applications as RDL, chip stacking/bonding and CMOS, where the organic polymer materials retain their photo-patterning integrity by reduced polymer reflow during high temperature curing. In particular, the pattern reflow is found to be significantly increased when using polymers featuring lower glass transition temperature (Tg) with flexible epoxy crosslinking agents. The pattern reflow is generally attributed to inefficient crosslinking during the curing stage.
Accordingly, there is still a need to develop self imageable photosensitive polymer compositions which feature efficient crosslinking properties, i.e., feature reduced pattern reflow during curing stage thereby retain high resolution achieved during photo-patterning step. Further, such efficient crosslinking should also improve various other properties, such as, i) maintain pattern integrity after cure, ii) improve bond adhesion, iii) minimize solvent swelling, i.e., improve chemical resistance, and iv) improve mechanical properties, just to name a few.